Video Encoding and Splicing for Tune-in Time Reduction in IP Datacasting (IPDC) Over DVB-H

Abstract

A novel video encoding and splicing method is proposed which minimizes the tune-in time of "channel zapping", i.e. changing from one audiovisual service to another, in IPDC over digital video broadcasting for handheld terminals (DVB-H). DVB-H uses a time-sliced transmission scheme to reduce the power consumption used for radio reception. Tune-in time in DVB-H refers to the time between the start of the reception of a broadcast signal and the start of the media rendering. One of the significant factors in tune-in time is the time from the start of media decoding to the start of correct output from decoding, which is minimized when a time-slice is started with a random access point picture such as an independent decoding refresh (IDR) picture in H.264/AVC. In IPDC over DVB-H, encapsulation to time-slices is performed independently from encoding in a network element called IP encapsulator. At the time of encoding, time-slice boundaries are not known exactly, and it is therefore impossible to govern the location of IDR pictures relative to time-slices. It is proposed that an additional stream consisting of IDR pictures only is transmitted to the IP encapsulator, which replaces pictures in a normal bitstream with IDR pictures according to time-slice boundaries in order to achieve the minimum tune-in time. It has to be ensured that the "spliced" stream resulting from the operation of the IP encapsulator complies with the hypothetical reference decoder (HRD) specification of H.264/AVC. A video encoding and rate control system is proposed to satisfy the HRD requirements for the spliced stream. Simulation results show that in addition to fulfilling HRD compliancy, good average quality of decoded video is achieved with minimum tune-in time